1. Field of the Invention
The present invention relates to a die trim assembly with a recess adapted to retain slugs in a stamping process. More specifically, the present invention describes an improved stamping die trim assembly that retains a slug within the die trim insert after it has been blanked. The present invention comprises a recess that can be added to new die trim inserts, or is retrofitted to die trim inserts in existing stamping dies. The recess improves stamping process and increases overall production for metal workers in various industries.
Stamping is a form of metalworking that uses a punch and a die to perforate holes or shapes in a part, or blanks out a part using punches. The waste portion that is stamped from the material is the slug. When stamping materials with a punch and a die, loose slugs can be tilted or pulled up and into the working area of a stamping die. This can cause the in-feeding material to jam, which can cause damage to the parts being made. Additionally, a slug that is pulled into the working area of the stamping die can damage or break the die tooling, which is expensive to repair or replace.
The present invention relates to a new and improved die trim assembly with a recess adapted to retain loose slugs during a stamping process. The recess preferably vertically aligned on the die insert. In one embodiment, the recess is created via a vertical conical extrusion, such that the top part of the recess is level with the top surface of the die trim section, and the depth of the recess into trim insert wall remains the same vertically along the interior wall of the die insert. In another embodiment, the recess is created via an angled conical extrusion, such that the top part of the recess remains level with the top surface of the die trim section and the bottom part of the recess is tapered inward into the slug cavity, becoming shallower. In yet another embodiment, the recess is created via an angled cylindrical extrusion. In this embodiment, the top part of the recess still remains level with the top surface of the die trim section, and the bottom part of the recess is tapered inward into the slug cavity, becoming shallower to a lesser depth into the trim wall. In all of the embodiments, the bottom of the recess creates a wedging action to hold a slug, which secures the slug in a die insert when stamping materials with a trim punch and a die. This counteracts the tendency for a trim punch to pull the slug upwards out of the die insert, which reduces damages to stamped parts and the die trim assembly.
The present invention can be added to new or existing die trim inserts by wire electric discharge machining (EDM) or conventional grinding or other suitable methods. The recess in the die trim inserts helps retain slugs, which reduces maintenance costs and expenses while increasing efficiency in production, benefiting manufacturing companies that use dies to stamp material or use any process that creates a slug using trim punches and die trim inserts.
2. Description of the Prior Art
Devices have been disclosed in the prior art that relate to die trim assembly parts to retain slugs. These include devices that have been patented and published in patent application publications. These devices generally relate to die trim assembly parts to retain slugs. However, the prior art fails to provide a device that can be easily added to both new and existing stamping dies that is similar to the present invention, which provides a cost-effective solution to improving the stamping process. The following is a list of devices deemed most relevant to the present disclosure, which are herein described for the purposes of highlighting and differentiating the unique aspects of the present invention, and further highlighting the drawbacks existing in the prior art.
These prior art devices have several known drawbacks. For example, U.S. Pat. No. 4,821,615 to Bakermans and Owzar discloses a slug retainer for the die trim assembly of a stamping and forming machine. This device comprises a slug receiving cavity that receives a slug. After slugs are punched from a material, they are pushed through one or two slug passageways in the die trim assembly. The slug receiving cavity communicates with the die trim assembly so that the slugs are continuously produced and stacked into the slug receiving cavity. Unlike the present invention, this device is needs to be affixed to a portion of the die trim assembly. As such, this device is limited to being anchored onto a new die trim assembly. Additionally, slugs can still be pulled into the working area before entering the slug receiving cavity, damaging the die trim assembly. The present invention is capable of retaining slugs immediately after it is punched from a material. Thus, this invention is not ideal as it cannot be retrofitted to existing die assemblies and problematic in securing loose slugs.
Similarly, U.S. Pat. No. 4,974,479 to Bakermans, Deimler, and Reavis discloses a system for controlling slugs in a stamping and forming machine. This device discloses a slug stripper that strips away any slugs that adhere to the end of the punch and slug supporting bars. One end of the slug stripper is mounted to the surface of the die trim section and the other end extends over the die opening. Because one end of the slug stripper extends over the die opening, it could potentially be snapped off or jammed into the die insert in case of malfunction. Unlike the present invention, the slug stripper needs to be mounted, most likely to a new die trim assembly, and maintained in the surface of the die trim assembly, which could be costly. Additionally, the slug stripper may wear down after repeated use, failing to retain slugs. In addition, the slug stripper can push loose slugs into the working area or loose slugs can adhere to the slug stripper, causing further damage to the entire assembly.
U.S. Pat. No. 5,035,163 to Bakermans discloses a punch and die combination for trimming the edges of strip material. The Bakermans device comprises multiple die opening with upstream and downstream shearing edges and multiple punches that punch out trapezoidal-shaped slugs. Unlike the present invention, the Bakermans device requires multiple die openings, where the loose slugs are stacked in the second die opening. While the second die opening may retain loose slugs, the purpose and design of the Bakermans device diverges in intent and design from the present invention, which discloses a recess for a single die opening adapted to secure loose slugs. The Bakermans device is also limited in the fact that the slugs are much more likely to adhere to the working area because the slugs are pushed through multiple die opening for edge trimming.
U.S. Pat. No. 6,997,363 to Vossen discloses a device for removing break-off components from a sheet of material. The Vossen utilizes a clamping tool to hold a waste portion of a metal after it is broken off. Alternatively, the Vossen device requires a high friction surface to hold waste portions when the clamping tool is not used. However, the invention described in Vossen requires additional parts for use with existing die assemblies and fails to address the issues of counteracting the tendency of the slugs to be withdrawn with the punch. The present invention addresses the issue by retaining loose slugs in a die insert by wedging a slug into a die insert interior without the need or expense to create additional apparatus to hold the slug.
U.S. Pat. No. 5,136,907 to Bakermans, Dubbs, and Holbrook discloses a punch and die trim assembly that pushes the slug into a die trim section opening. The slug is moved laterally across the face of the punch by the rib, and the slug moves against the surface of the opening as it is pushed into the die opening and moves downwardly relative to the inclined rib. This is disadvantageous because the punch and the die insert must be aligned to prevent the punch from shearing the rib, which can damage the punch and the rib. This device also fails to address the issues of the slug adhering to the face of the punch while it is moved against the surface of the opening, and further does not address the ability to remove any loose slugs that adhere to the face of the punch. The present invention does not require moving the slugs laterally across any surface. The slugs are simply pushed into the die insert after it is punched. Additionally, the prior art discloses tapered die insert walls, which reduces the life of the die insert because the opening may be enlarged over use. This increases clearance of the apparatus, which can lead to burrs.
The present invention is adapted to retain slugs that is not limited by the structure of the die trim assembly being installed thereinto. The present invention provides flexibility with regard to the size and shape of the recess and where the recess can be added. Multiple recesses can be added, depending on the size of the loose slugs and the type of material used for stamping. The present invention will greatly assist metal workers using stamping machines or die trim assemblies by retaining and securing loose slugs during a stamping process. It is therefore submitted that the present invention substantially diverges in design elements from the prior art and consequently it is clear that there is a need in the art for an improvement to slug retainer devices. In this regard, the instant invention substantially fulfills these needs.